Backdoor trojans and rootkits represent two of the fastest growing malware expunged by Microsoft's Windows Malicious Software Removal Tool (MSRT), which was unveiled in January 2005.
The software giant today released a report documenting trends in the type of malicious software cleaned by the tool in an attempt to shed light on the current threat landscape.
According to the report, the MSRT - free for licensed Windows users - has been executed 2.7 billion times by at least 270 million unique computers. It has removed malware from 5.7 million computers, or one instance for every 311 computers on which it runs.
Among the report's major findings:
Backdoor trojans made up the most prevalent threat removed by the tool, followed by email worms, rootkits, peer-to-peer worms, exploit worms, viruses and IM worms, the report said.